The present invention relates generally to containers for holding liquids, reagents, and materials, for testing, analytical procedures, and performance of chemical reactions. It is particularly applicable, but in no way limited, to multi-well plates.
Multi-well plates, or two-dimensionally bound arrays of wells or reaction chambers, are commonly employed in research and clinical procedures for the screening and evaluation of multiple samples. Multi-well plates are especially useful in conjunction with automated thermal cyclers for performing the widely used polymerase chain reaction, or xe2x80x9cPCRxe2x80x9d, and for DNA cycle sequencing and the like. They are also highly useful for biological micro-culturing and assay procedures, and for performing chemical syntheses on a micro scale.
Multi-well plates may have wells or tubes that have single openings at their top ends, similar to conventional test tubes and centrifuge tubes, or they may incorporate second openings at their bottom ends which are fitted with frits or filter media to provide a filtration capability. As implied above, multi-well plates are most often used for relatively small scale laboratory procedures and are therefore also commonly known as xe2x80x9cmicroplatesxe2x80x9d.
Multi-well plates for PCR use are typically comprised of a plurality of plastic tubes arranged in rectangular planar arrays of typically 3xc3x978 (a 24 well plate), 6xc3x978 (a 48 well plate) or 8xc3x9712 (a 96 well plate) tubes with an industry standard 9 mm (0.35 in.) centre-to centre tube spacing (or fractions thereof). As technology has advanced plates with a larger number of wells have been developed such as 16xc3x9724 (a 384 well plate). A horizontally disposed tray or plate portion generally extends integrally between each tube, interconnecting each tube with its neighbour in a cross-web fashion. In the case of multi-well plates that are of the non-filtration variety, the bottoms of the tubes may be of a rounded conical shape (as generally used for thermal cycling and to ensure complete transfer of samples), or they may be flat-bottomed (typical with either round or square-shaped designs used with optical readers). Multi-well xe2x80x9cplatesxe2x80x9d may also exist in a xe2x80x9cstripxe2x80x9d form wherein a single planar row of interconnected tubes is provided.
It will be apparent that as many as 96 individual reaction mixtures can be simultaneously subjected to, for example, PCR treatment by placing a single multi-well plate within a thermal cycler unit. Most commercial thermal cyclers that are presently available have heating/cooling blocks with conically shaped depressions, typically 96 in number, which are specifically designed and arrayed for mateably receiving the lower portion of the tubes of multi-well plates so that intimate and uniform heating of the PCR reaction mixtures contained within the wells (tubes) may occur.
With the variety of operations and reaction conditions available to the scientist there is an increasing requirement to operate on a variable number of samples. In addition, it is often necessary to carry out subsequent operation(s) on just a portion of samples which have undergone a first processing. In order to achieve this the samples must be subdivided into subsets for further investigation/reaction. This can currently be achieved by using a number of small plate arrays to total 96 and by selecting just some of the plate arrays for subsequent processing. For example, one could choose two 3xc3x978 plates and one 6xc3x978 plate to give a fill 96 well cycler. Alternatively, a conventional 96 well plate can be used and this can be physically cut up into smaller arrays at a suitable point or points in the process. However, both these methods have inherent disadvantages.
Firstly, pre-selecting plate blocks requires considerable pre-planning and also presupposes the results of the first set of reactions. Once chosen, there is no subsequent flexibility as to the number in each block. In addition, this method greatly increases the number of manual handling operations since each block must be picked up separately. Furthermore, these smaller blocks are generally not amenable to robotic handling, whilst conventional 96 and 384 multi-well plates are routinely handled robotically.
Cutting up conventional plates has the advantage that the size of the subsets can be determined by the operator at any time, providing increased flexibility. However, once the plates have been cut manually they can only be placed in a thermal cycler in their original orientation. Inevitable irregularities in the cuts means the subsets will only fit together to reform the original plate. Manual cuts are never entirely straight and the misalignment of adjacent blocks prevents them sifting properly in the cycler in anything other than their original configuration. This is usually overcome by leaving a gap of one row of wells between adjacent blocks. This in itself is unsatisfactory because it means that extra runs of the cycler may need to be carried out to make up for the empty rows.
It is the object of the present invention to provide multi-well plates which overcome or mitigate some or all of these problems.
According to the present invention there is provided a multi-well plate comprising a plurality of discrete tubes held together in an array by a plate portion, characterised in that one or more section lines are provided in the plate portion in pre-determined regions, said section lines being adapted to facilitate dividing up the multi-well plate into sub-units of a pre-determined size.
Forming section lines in the plate either during the moulding process or subsequently, enables the operator to divide the plate into smaller sub-units which will still fit together side by side in a thermal cycler or the like.
Preferably the section lines are formed by a score line extending across the width of the plate. A score line is defined as any feature which facilitates the separation of the plate into sub-units.
Preferably the section line or score line comprises one or more apertures extending through the thickness of the plate portion. By forming a series of apertures, preferably elongate in shape, the plate can easily be separated into sub-units.
In a particularly preferred embodiment the section line incorporates one or more lugs connecting adjacent sub-units. Preferably the lugs are of a snap-off construction, such that the lugs associated with a section line can be removed in the event that plate is divided into sub-units along that section line.
These lugs provide the plate with rigidity when it is in its original configuration before subdivision. However, the lugs are easily removed when the plate is sub-divided. For example, the lugs may be substantially circular regions which extend across the section line. They may be partially punched out or weakened around their circumference for ease of removal.
Alternatively the section line may comprise a pull-out strip or a series of perforations.
Preferably the plate incorporates a skirt around the perimeter of the plate in order to increase the rigidity of the plate. The skirt also provides space upon which to label the plate and its individual sub-units.
In a particularly preferred embodiment the skirt incorporates gaps at strategic points to facilitate robotic handling.
In a further preferred embodiment the rim of each tube in the multi-well plate extends proud of the plate portion.